READING keeps its secrets well. Some might call the town 60 kilometres west of London undistinguished. Exotic is certainly not the word. But hidden in a walled garden in a field to the south of the town is a destination both special and unique. Without what goes on inside a huge white tent here, chocolate would hit a rocky road – and not the sort with marshmallows. This is the International Cocoa Quarantine Centre.
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Chocolate is the world’s favourite treat: globally, we eat 7 million tonnes of the stuff a year, and demand is rising as Asian consumers develop a taste for it, too. Yet supply is far from assured. Most of the world’s commercial cocoa plants originate from just a few clones made in the 1940s, which have so far proven productive enough to keep up with demand. But this has led to a dangerous lack of genetic diversity, leaving cocoa vulnerable to a host of pests and diseases that love cocoa as much as we do. Some 30 to 40 per cent of the crop is lost to disease each year, and there are fears that climate change might exacerbate the problem.
The drive to breed new cocoa varieties that are more productive, as well as hardy and pest-resistant, means sending specimens around the world, which risks spreading disease and making matters worse. That’s why since 1985 the vast majority of cocoa samples being transported to distant regions have made a two-year pit stop.
“Reading is the hub these days for the international movement of cocoa,” says Andrew Daymond, not a little proudly. A plant physiologist at the University of Reading, he is in charge of cocoa quarantining.
Entering the tent, I am transported to the tropics. A wall of heat and humidity hits me, plus the striking sight of hundreds of 2-metre-tall plants, lush and green, some with large orange or red pods hanging from their trunks. Daymond walks me through the aisles of trees, pausing to cut off a wrinkly, yellow pod. He slices it open to reveal a white, slimy pulp with fat, brown seeds nestled inside. The seeds are bitter, with only a hint of a chocolately taste. It is only when they and the pulp are fermented, and the seeds dried and roasted, that the characteristic toothsome flavour begins to emerge.
“Why Reading?” I ask. It is a world away from the tropical forests of South America where cocoa naturally grows. That’s exactly the point, says Daymond. If a pathogen should escape, it wouldn’t survive long in the temperate UK climate and there are no crops from its native land for it to infect.
In quarantine, Daymond and his team are on the look out for pod-rotting fungal diseases such as witches’ broom and the festive-sounding frosty pod, both of which spread easily. In the 1990s, witches’ broom devastated cocoa production in the state of Bahia in Brazil, after spores were brought in from the Amazon region, perhaps deliberately. The output from the Bahia region plummeted by 75 per cent. So far, neither disease has reached West Africa, where most of the world’s cocoa is now grown. There, they have different problems: the bug-borne disease swollen shoot virus, which kills cocoa trees within a few years, and mirid bugs, which feed on the pods, slashing yields by up to 40 per cent.
Cocoa samples arrive in Reading as budwood: a short stick with a number of active buds sprouting on it. Around 30 new varieties turn up each year, some of them wild plants from rainforest expeditions. On arrival, the samples are inspected for obvious signs of insect stowaways. Buds are then grafted on to seedlings to establish a mother plant. To check for less conspicuous problems, buds from the mother plant are also grafted on to seedlings of an “indicator” plant, a variety of cocoa that shows disease symptoms more clearly than most. If viruses or other diseases are present in a sample that comes in, the symptoms will eventually develop.
After two years, the team can be confident that any dormant viruses will have shown up, and the plant is deemed safe. Genetic tests under development at the University of Reading could offer a way to speed up the quarantine process, but Daymond says he is not yet certain these tests can pick up all of the viruses.
When the cocoa plants are certified disease-free, cuttings are sent to researchers around the world. One of these is Wilbert Phillips-Mora, a specialist in cocoa diseases and head of the breeding programme at the Tropical Agricultural and Higher Education Center (CATIE) in Costa Rica. For decades, he has been painstakingly mixing promising strains to create hybrids that are screened for disease resistance. “We are refreshing the blood of cocoa,” says Phillips-Mora. One new variety he has developed, CATIE R6, not only shows remarkable resistance to frosty pod, but also delivers a huge boost in productivity. The chocolate icing on the cake was when it was commended in the International Cocoa Awards in 2009 for its taste and aroma.
Quite a hill of beans
New varieties such as CATIE R6 are sent to researchers in other nations to be hybridised with the native crop and rolled out to farmers. In West Africa in particular, where many plantations are reaching the end of their productive life this new blood is sorely needed.
The quarantine greenhouse is large enough to cover four tennis courts, and much of it is filled with plants that have already received the all-clear – 400 different varieties. Plants still under quarantine are housed separately.
Has anyone made chocolate from the Reading crop, I ask Daymond, hopefully. “It’s not something we’ve tried,” he says. “You need a large heap of beans to do a proper fermentation of cocoa beans, and we don’t get huge numbers of pods here.”
Undeterred, when I get home, I decide to give it a go. I put the contents of the single cocoa pod that Daymond gave me into the most tropical conditions I can find, next to the hot water tank. First I need to let the pulp ferment into an alcoholic liquid to break down the astringent compounds in the seeds. Then I can dry and roast the seeds in the oven. Easy. Or not, as it turned out. After a few days, I found myself with a handful of black, mouldy beans and an aroma that was anything but delicious.
Perhaps leave the chocolate-making to the experts, and savour the flavour – with the exotic taste of Reading in every bite.
This article appeared in print under the headline “Chocs away”